*2.7. Scanning Electron Microscopy*

Scanning Electron Microscopy (SEM) is a technique that is used to observe the surface structure of materials at high magnification. In the case of edible films, SEM is used to study their physical characteristics, such as their microstructure, uniformity, compactness and surface texture. SEM imaging can also help to identify any defects in the film, such as cracks, pores, or voids, that could impact its functionality and performance as food packaging. The SEM results of the SA–AG film samples with the added CEO are shown in Figure 2. The control film (AC-1) containing SA and AG without the CEO showed a structure with some pores on the film surface, compared with the films loaded with CEO. The protrusion can also be observed in the cross-section image of the AC-1 sample. The randomly distributed oil drops can be observed on the film surface of the AC-2 sample. The roughness of the AC-2 film samples could be linked to the agglomeration that resulted from the irregular distribution of hydrophobic components during the film-forming procedure. The most uniform dispersion was observed in the AC-4 sample, which contained the maximum concentration of the CEO. The film samples incorporated with the CEO showed smooth surfaces with a fewer number of particles, homogeneous structures, and no pores and cracks. Zhou et al. [20] also reported similar results, in which the CEO distributed homogeneously in the polymer matrix of cassava starch-based films. Moreover, the interaction between oil and the film-forming polymers can also influence the SEM appearance, as some polymers may be more compatible with oil than others.

pearance, as some polymers may be more compatible with oil than others.

study their physical characteristics, such as their microstructure, uniformity, compactness and surface texture. SEM imaging can also help to identify any defects in the film, such as cracks, pores, or voids, that could impact its functionality and performance as food packaging. The SEM results of the SA–AG film samples with the added CEO are shown in Figure 2. The control film (AC-1) containing SA and AG without the CEO showed a structure with some pores on the film surface, compared with the films loaded with CEO. The protrusion can also be observed in the cross-section image of the AC-1 sample. The randomly distributed oil drops can be observed on the film surface of the AC-2 sample. The roughness of the AC-2 film samples could be linked to the agglomeration that resulted from the irregular distribution of hydrophobic components during the film-forming procedure. The most uniform dispersion was observed in the AC-4 sample, which contained the maximum concentration of the CEO. The film samples incorporated with the CEO showed smooth surfaces with a fewer number of particles, homogeneous structures, and no pores and cracks. Zhou et al. [20] also reported similar results, in which the CEO distributed homogeneously in the polymer matrix of cassava starch-based films. Moreover, the interaction between oil and the film-forming polymers can also influence the SEM ap-

**Figure 2.** Scanning Electron Microscopy of SA–AG hydrogel-based edible films; AC-1/ Control, AC-2 contains 15 μL of CEO, AC-3 contains 20 μL of CEO, and AC-4 contains 30 μL of CEO. **Figure 2.** Scanning Electron Microscopy of SA–AG hydrogel-based edible films; AC-1/Control, AC-2 contains 15 µL of CEO, AC-3 contains 20 µL of CEO, and AC-4 contains 30 µL of CEO.

#### *2.8. X-ray Diffraction Analysis 2.8. X-ray Diffraction Analysis*

XRD analysis of edible films is important because it provides important information about the structure and composition of the material. XRD provides information about the crystalline structure of edible films, which provides insight into their mechanical properties, such as their tensile strength and flexibility. The SA–AG hydrogel-based composite films loaded with the CEO were examined for their structural characteristics and the resulting spectrum is shown in Figure 3. A Diffract Eva software package was used to calculate the crystallinity percentages of the film samples, and the crystallinity percentages of the AC-1, AC-2, AC-3, and AC-4 samples were found to be 38.1%, 38.7%, 35.4%, and 38.6%, respectively. All the samples showed characteristic peaks at similar positions with different intensities due to the variations in the concentration of the oil. However, there was no difference observed in the crystallinity of the SA–AG composite hydrogel films with the addition of the CEO. Overall, the XRD patterns showed good compatibility between the film-forming polymers including SA, AG and CEO.

tween the film-forming polymers including SA, AG and CEO.

XRD analysis of edible films is important because it provides important information about the structure and composition of the material. XRD provides information about the crystalline structure of edible films, which provides insight into their mechanical properties, such as their tensile strength and flexibility. The SA–AG hydrogel-based composite films loaded with the CEO were examined for their structural characteristics and the resulting spectrum is shown in Figure 3. A Diffract Eva software package was used to calculate the crystallinity percentages of the film samples, and the crystallinity percentages of the AC-1, AC-2, AC-3, and AC-4 samples were found to be 38.1%, 38.7%, 35.4%, and 38.6%, respectively. All the samples showed characteristic peaks at similar positions with different intensities due to the variations in the concentration of the oil. However, there was no difference observed in the crystallinity of the SA–AG composite hydrogel films with the addition of the CEO. Overall, the XRD patterns showed good compatibility be-

**Figure 3.** X-ray diffraction pattern of SA–AG hydrogel-based edible films; AC-1/blank, AC-2 con-**Figure 3.** X-ray diffraction pattern of SA–AG hydrogel-based edible films; AC-1/blank, AC-2 contained 15 µL of CEO, AC-3 contained 20 µL of CEO, and AC-4 contained 30 µL of CEO.

tained 15 μL of CEO, AC-3 contained 20 μL of CEO, and AC-4 contained 30 μL of CEO.
